Power-operated antenna



R. H. WISE POWER-OPERATED ANTENNA Feb. 23, 1960 2 Sheets-Sheet 1 Filed April 26, 1955 2 L U S m INVEN TOR. RALPH H. WISE ATTORNEY Feb. 23, 1960 R. H. WISE 2,926,351

POWER-OPERATED ANTENNA Filed April 26, 1955 2 Sheets-Sheet 2 INVENTOR. RALPH H.W|SE

ATTGRNEY'L' POWER-OPERA'EED ANTENNA Ralph H. Wise, Gary, Ind., assignor, by mcsne assign- ;nlliits, to The Anderson Company, 'a corporation ofv n ana l Application April 26, 1955', Serial No. 503,39

14 Claims. (Cl. 343-903) The present invention relates to a power-operable' vehicle antenna and more particularly to ap-ovfer-operated radio antenna for an automobile, or the like.

Although at iirst blush the design of a power-operable radio antenna for .an automobile or the like appears to be quite simple, ,the number of prior patented designs which have not been commercially produced serves to illustrate A commercially successful power-operable vervelatively movable parts thereof; the actuating mechanism must be electrically isolated from the antenna components; and the antenna should be iittcd with seinemechanism for indicating when the antennais retracted. Prior to -the instant invention, there has not been provided a commercially successful power-operable vehicularan- `vtenna lift which has satisfied all of these requirements.

The present invention provides an improved antennaactuating mechanism which fulfills the requirements hereinbefore set forth. The mechanism includes a flexible driving cable having a threaded periphery and an actuating mechanism cooperating with thev threaded `cable periphery to extend or retract the telescoping antenna masts when the' motor for energizing the actuating means is operated. The positive' threaded drive between vthe actuating mechanism andthe driving cable will -serve to exert the full power of the motor upon the telescoping antenna elements, and the use of a ilexiole driving cable accommodates tue fitting of complete actuating mechanism within the contines of an automobile body panel, or the like. The antenna proper includes a pair `of telescoping mast sections, the inner of which is axially movable through the outer section for antenna extension or retraction. When the driving cable is extended `by the actuating mechanism, it lies within the outer mastsection, and the outer mast is insulated from the inner mast by a sleeve of insulating material so as to prevent grounding ofthe antenna through the actuating cable and the motor. However, vupon full antenna retraetion, theinner ,mast enters the contines of the 'motor beyoudthe' insulating sleeve, so that the antenna is Agrounded out through the motorl to give an audible indication, by means of subsigutially diminished volume, thatrthe antenna has been It is, therefore, an important object ofthe present invention to provide'an improved power-operable vehicle antenna.' 1 1 'L y Another important object of thepresentinvention `is the provision of a power-operated radio. antenna for an. automobile or the like utilizing a flexible driving cable having a ythreaded periphery engaged by a plurality of actuating nited Stats lPaten-C 2,926,351 Patented Feb. 23, 1960 'ice `cable having a threaded periphery, and a plurality of thread-engaging elements engaging a portion of the cable periphery and being driven by a power means to advance or retract a cable, thereby advancing and retracting the antenna mast sections.

Other and further important objects of the present invention will become apparent from the drawings annexed hereto and the detailed description which follows hereinafter, together with the appended claims. r- On the drawings: Figure l is a fragmentary sectional view, with-parts shown at elevation, lshowing an antenna of the lpresent 'invention mounted upon an automobile;

Figure 2 is an enlarged view, similar to Figure 1, illusl trating the' antenna alone;

Figure 3 is a greatly enlarged axial sectional view of a portion of the antenna shown in Figure 2;

Figure 4 1s a greatly enlarged axial sectional view, similar to Figure 3, with parts shown in elevation, illustrating the remainder of theantenna of Figure 2;

Figure 5 is a greatly enlarged axial sectional vieA further illustrating a `portion of the antenna; v l

Figure is a greatly enlarged axialsectional view illustrating the antenna-actuating mechanism;

Figure 7 is an exploded perspective-view of a portion of the antenna-actuating mechanism;

Figure .8 is a greatly enlarged fragmentary secv'onal View illustrating the cooperation or the various parts o'f the actuating mechanism. i

As shown in the drawings: v

ln Figures l and 2, reference numeral l0 refers generally to anantenna of the present invention which cornprises a generally tubular outer mast section lit and a cylindrical or rodlike inner mast 12 which is axiallytelescopable within the outer mast il. f

As best shown in Figures 3, 4, and 5, the outer mast 1 1 is apertured to snugly receive the inner mastsection i2 therethrough. A` generally cylindrical cap 14 having an inturned upper annular flange 15 is telescoped overthe outer periphery of the upper end of the mast, and a waterproof seal 1 6, formed of felt or the like, is interposed between a ange 13 on the outer mast 1l and theilange 15 on mast 1 2 to prevent the entry of water, snow, ice,

.or the like, between the two mast sections l1 and 12.

Zand-a collar Zil'having asmoothly' cylindrical axial operii'ngis'snugly tted about the lower end of the oui-ermast 11; the collar 20 being secured to the mast i1 by suitable means, as byweldingindicated at 2l." 1- l .I 'il' The outer surface of the collar-'20 'is polygonal' in shape, preferably octagonal, and is surrounded by anclatively -thick insulating element 22, preferably' formed? of an elastomeric material such as rubber, which is Sur- 'sleeve 25 may be formed of any suitable insulating material, preferably woven or matted fiberglass fibers impregnated with a synthetic resinous material.

The sleeve 25 terminates at its lower end in a radially outwardly flared flange 26 which is confined between the bevelled edge 19 at the extreme lower end of the outer mast 11 and an insulating plug 27, preferably formed of a polyamide resin, such as nylon, having a cylindrical bore 28 of substantially the same size as the bore 29 of the sleeve and an outer exterior surface snugly conforming to the inner cylindrical contour of the bushing 20.

The plug 27 and the bushing 2t) are secured together by suitable means, as by staking, indicated at 30. The upper free end of the plug 27 is chamfered, as at 31, for cooperation with the chamfer 19 on the outer mast 11 to confine the sleeve flange 26 therebetween. In assembly of the portion of the antenna lift shown in sleeve is positioned with its flange 26 abutting the chamfered portion 19 of the outer mast and with the bushing 20 welded to the outer mast, as at 21. The plug 27 is then inserted into the outer mast and is staked to the Figure 5, the

collar to secure the sleeve 21, the outer mast 11, the

sleeve 20, and the plug 27 in a unitary assembly.

As best seen in Figure 2 of the drawings, the intermediate casing section 23 has its lower end secured, as by welding, to a bearing cap 32 of a reversible electric 'motor 33, and its upper end secured to a mounting cup 34 adapted to abut the inner surface of an automobile body panel 35. The extreme upper end of the intermediate casing 23 is threaded, as at 36, for the reception of a nut 37 which urges an upper mounting cup 35a against the upper surface of the body panel 35. An elongated axial bushing 38 is interposed between the upper end of the intermediate casing 23 and the outer mast 11 to insulate the outer mast from the body panel and the intermediate casing 23. The lower end of the insulating bushing 38 is provided with an internal annular shoulder 39 and with a second, radially larger annular shoulder 40 against which are respectively seated the upper end and an intermediate annular shoulder formed on a generally cylindrical conductive Wiper 41, preferably formed of brass or the like. The wiper 41 is in good electrical contact with the outer mast element 11, and is provided with a radial threaded aperture 42 receiving a lead-in contact 43 by means of which the antenna is connected to the vehicle radio. The leadin 43 is surrounded by a threaded bushing 44 for facilitating connection of the leadin to the radio.

The electric motor 33 is enclosed within a casing 45 carrying spaced bearings 46 for journaling a hollow, generally cylindrical armature shaft 47 which is rotatable whenever the motor is energized. This shaft has secured thereto at its lower end (Figure 4) a mounting collar 48 secured to the shaft by a set screw 49 and having secured to its lower end by suitable means, as by welding, brazing, or the like, an actuating mechanism indicated generally at 50.

This actuating mechanism comprises a bridging element 51 having outwardly and downwardly deflected end portions 52 which are secured, as by rivets 53, to a pair of superimposed carrier plates 54 and 55. These carrier plates are better illustrated in Figures 6 and 7; the plate 54 having an upwardly displaced medial portion 56 having a centrally located aperture 57, and the lower carrier plate 55 having a downwardly displaced medial portion 58 provided with a centrally located aperture 59. The

plates 54 and 55 are adapted to be secured together by the same rivets 53 whichv secure the plates to the bridging element 51, and the displaced medial portions 56 and 58 of the plates cooperate to define therebetween a pocket in which are disposed a plurality (three in the illustrated embodiment of the invention) of thread-engaging elements 60.

These thread-engaging elements are particularly shown in Figure 8 from which it will be seen that each of the elements comprises a pair of axially spaced, generally toroidal thread-engaging portions 61 joined by a generally concave intermediate portion 62 for a purpose to be hereinafter more fully described. The elements 60 are also provided with end pintles or axle portions 63 which project axially from the element 60 into sockets 64 formed in the displaced portions 56 and 58 of the elements 54 and 55, respectively. The sockets 64 are provided by merely dimpling the displaced portions 56 and 58 to provide seats within which the axle portions 63 of the thread-engaging elements 60 are seated. The offset medial portions 56 and 58 of the carrier elements 54 and 5S, respectively, are of themselves further offset vertically, as illustrated in Figure 7, to vertically space the thread-engaging portions 61 of the respective threadengaging elements 60 in order that the thread-engaging portions 61 can properly cooperate with a threaded element, as will be hereinafter described.

The registering apertures 57 and 59 in the carrier elements 54 and 55, respectively, receive therethrough a flexible cable indicated generally at 70 in Figures 3 and 4, and particularly illustrated in Figures 6 and 7 as comprising a woven core 71 which is flexible and which has wrapped thereabout one or more peripheral wires 72 which are wound helically about the core 71 and which project radially therefrom to define a threaded periphery for the cable assembly 70. The wires 72 are tightly wound upon the core 71 so as to become partially imbedded therein (Figure 8) but appreciable portions of the wire do project radially beyond the core 71, so that the thread-engaging portions 61 of the elements 60 may contact the periphery of the wires 72. Intermediate the wires 72 are spirally wrapped a plurality of smaller wires 73 which serve merely to space the wires 72 and which are not engaged by the thread-engaging elements 60.

The upper end of the cable 70 is connected to the lower free end of the inner mast element 12 through an insulated connector 75 (Figure 3), which is preferably formed of fiberglass filaments impregnated with a synthetic resin. The free lower end of the inner mast 12 is provided with an axial aperture 76 into which is inserted one end of the connector 75, this one end of the connector being provided with a reduced diameter portion 77 into which the walls of the recess 76 in the element 12 are deformed or staked to permanently attach the connector 75 to the mast element 12. The lower end of the connector 75 is inserted into an originally cylindrical fitting 78 which is likewise deformed into a groove 79 in the connector; the other end of the fitting 78v being de formed into a similar groove 80 formed in the upper end of the core 71 of the cable 70. The lower end of the inner mast 12 is thus permanently attached, against both relative rotation and axial separation, to the upper end of the core 71 of the cable 70. The inner mast 12, and the cable 70 are prevented from rotating within the outer mast 11 by the cooperating key 17 and slot 18 heretofore described.

The free lower end of the cable 70 is provided with an abutment collar 80 circumferentially encircling the cable 70 and adapted to abut a resilient stop 81 on the lower bearing cap 32a (Figures 4 and 7). The resilient stop 81 comprises an elastomeric grommet 82 having a peripheral groove seated in an aperture of the lower motor bearing cap 32a, and a metal sleeve 83 having an outturned lower flange 84 underlying the grommet 82 and an upper outwardly turned flange 85 confining a lock ring 86 between the flange 85 and the grommet 82.

The lowerend of the cable 76 axially enters a protective casing 87 formed of flexible tubular material,

gli!

such as a plastic material. As illustrated in Figures 1 'and '2, the lcasing 87 may be freely distorted withinthe body panel 35 in order to accommodate the antenna for iitting withir the confines of the vehicle with which the antenna is associated. p The flexible cable 70 will freely adjust itself to the contour of the flexible casing 87.

Operation The operation of the antenna of the present invention will be readily evident to those skilled in the art. However, a brief description of its operation will be given in order to facilitate an understanding of the advancement in the art which is providedy by the present invention.

The'reversible motor 33V is connected, as by electrical wiring 90, to a source of power, preferably the automobile battery, through a conventional two-way switch,

so that the motor may be operated in either direction. When the motor is operated inV a direction to drive the inner mast 12 for elevation, the armature shaft 47 is rotated by the motor `to rotate the actuating mechanism S through the bridging element S1 and the carrier plates 54 and 55. The carrier plates rotate the thread-engaging elements'tl in an annular path, and engagement of the thread-engaging portions 61 of the elements 6l) with the peripheral heiically wound wires 72 of the cable 70 movesl the antenna inner mast 12, which is held against rotation by the key 17, upwardly through -the outer mast 11.

As illustrated in Figure 8, the toroidal thread-engaging portions 61 are in substantially point-topoint contact with the helically wound wires 72 with-the concave portion 62 being spaced from the wire periphery to prevent binding of the elements 60 upon the wires 72.

inasmuch as the cable 70 cannot rotate, because of t its nonrotative engagement with theinner mast 12 which is retained against rotation by the cooperating key 17 and slot 1S, the cable 7? will be driven through the armature shaft from its lowered position shown in Figure 4 to its elevated position shown in Figure 3.

Because of the insulating sleeve 25 which is interposed between the xed outer mast 11 and the movable inner mast 12, entry of the cable into the outer mast will not cause grounding of the antenna through the cable and the motor, even though the cablemay be distorted within the outer mast to lie against the inner periphery thereof. The cable will stop its upward movement at any time when energization of the motor 47 is interrupted, or upward movement will cease, even upon continued switch depression, when the abutment 80 at the tail end of the cable contacts the resilient stop Si. Contact between the abutment 80 and the resilient stop 8l will not place any appreciable shock load upon the mechanism because of the provision `of theresilient bushing 82, and the only'load imposed on the cable will be a tensile strain exerted on that portion of the cable between the lower stop 80 and the actuating means 5G. To lower the inner mast 12, the motor is merely operated reversely, so that the cable is pulled` downwardly through the armature shaft 47 through rotation ofthe threadengaging elements 60 by the motor.

One desirable feature of the present invention occurs upon retraction of the inner mast ll2 to such an extent that the lower end of the inner mast passes the extreme lower end of the insulating sleeve 2S and enters the motor armature shaft 47. At this time, there is no insulation between the antenna and the motor, and the antenna will accordingly be grounded out through the motor. This grounding of the antenna will cause a substantial diminution in the volume of the associated radio, thus giving an audible indication of substantially complete antenna retraction. Downward movement of the antenna section 12 will continueuntil the key 1'7 strikes the upper end l8r: of the keyway 18 in the inner mast l2. i

'geneest The advantages residingin the present invention are numerousrand include, first, the provision of a positive antenna drive which is capable of overcoming the extreme resistance to antenna movement caused by snow or ice'between the antenna sections, rusting of the antenna, or for other reasons; second, the utilization of a flexible cable itl capable of positivelydriving the antenna `mast section 12, so that the positive-drive antennalift may be fitted within the contines of an automobile; third, the provision of means for audibly indicating antenna retraction, giving the vehicle operator a positive indication of the antenna signal-receiving capabilities regardless of the location of the antenna at the rear of the car, the top of the car, or some other location in which the antenna itself is not readily Visible; and the provision of means for positivelyl electrically isolating the antenna from the motor and the remainder of the actuating mechanism, so long as the antenna is not substantially fully retracted.

lt will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention, and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim: v .Y

1. A power-actuated antenna comprising an outer antenna section fixedly attachable to avehicular body cornvponent, a movable inner antenna section telescopically retractible into and extensible beyond said outer section, said antenna sections being electrically connected, a reversible threaded actuating cable insulatedly secured to said inner vsection and movable axially through said motor shaft and said outer section, a plurality of thread-engaging elements mounted on said motor shaft and having peripheral 4portions engaging the cable thread toadvance or retract the cable upon energization of said motor, insulating material interposed between said inner and outer sections whereby said cable is insulated from the antenna sections, and contact means on said inner section whereby entry of said inner section into the motor grounds out the antenna through the motor upon retraction of said inner section.

2. A power-actuated antenna comprising an antenna section extensible beyond a surrounding case to enhance signal reception therethrough an actuating cable having a spirally Wrapped peripheral wire deiining a peripheral cable thread of appreciable axial lead, insulated connecting means securing said cable to said antenna section against relative axial and rotational movement, rotary power means, a driving assembly including a carrier driven by said rotary power means and encompassing a portion of the threaded periphery of said cable, and a plurality of thread-engaging elements carried by said carrier and each having axially spaced toroidal peripheral'portions engageable with the peripheral wire of said cable to advance the cable and the antenna section to an-extended position.

3. In an extensible antenna having inner and outer relatively movable telescopic sections electrically connected together, the inner of which is extensible from'a retracted position within the outer section to an extended position at which the inner section projects beyondthe outer section, a reversible electric motor having a shaft provided with an axial bore, insulating material interposed between said inner and outer sections and terminating short of said motor shaft, and an actuating cab-le secured to said inner section and passing through the shaft bore of said motor, said cable having a threaded periphery and a nut assembly drivingly secured to said motor shaft and engaging said cable periphery to advance and retract said inner section thereby, said cable entering said outer section during extension of the inner section in insulated relation to said outer section, said inner section entering 7 the bore of said shaft upon retraction of said inner section to ground out the antenna through said motor.

4. A vehicular antenna comprising a plurality of electrically connected relatively telescopically movable antenna mast sections including an inner section axially movable from a lower retracted nonreceiving position to an upwardly extended signal-receiving position and an outer section telescopically axially receiving said inner section therein when said inner section is in its retracted position with the inner section lower end projecting axially below said outer section, energzable power means for moving said inner section from either of its said positions to the other of said positions and including a reversible electric motor having a hollow motor shaft axially aligned with and receiving the lower end of said inner section in retracted position, a flexible cable threaded through said motor shaft and insulatedly connected to said inner section, said cable having a helically threaded periphery, said cable being axially extensible into said outer section upon energization of said motor to advance said inner section to its extended position and being retractible beyond the confines of said outer section upon retraction of said inner section, thread-engaging means rotatable with the motor shaft and engaging said cable to advance and retract the same, and an insulating sleeve interposed between said inner and outer mast sections, said sleeve electrically isolating the outer section from the cable upon extension of said inner section, said inner section lower end portion projecting into the hollow motor shaft when the inner mast is retracted to thereby ground out the antenna.

5. A power-actuated antenna comprising an outer antenna section fixedly attachable to a vehicular body component, a movable inner antenna section electrically connected to and telescopically retractible into and extensible `beyond said outer section, a reversible motor having a holl-ow rotatable shaft axially aligned with said inner antenna section, a peripherally threaded actuating cable insulatedly secured to said inner section and movable axially through said motor shaft and said outer section, means on said motor shaft threadedly engaged with the periphery of said cable to advance or retract said cable upon energization of said motor, an insulating sleeve interposed between said inner and outer sections and terminating short of said motor shaft, whereby said cable is insulated from the antenna sections, and contact means on said inner section whereby entry of said inner section into the motor grounds `out the antenna through the motor upon retraction of said inner section.

6. A power-actuated antenna comprising an antenna section extensible beyond a surrounding tubular section to enhance signal reception therethrough, an elongate actuating element having a threaded periphery of appreciable axial lead, insulated connecting means securing said cable to said antenna section, rotary power means, a driving assembly including a carrier driven by said rotary power means and having an aperture receiving said cable therethrough, and a plurality of thread-engaging elements carried by said carrier and having toroidal peripheral portions overhanging said aperture to continuously engage the cable periphery for advancing the cable and the antenna section to an extended position or to a lowered position.

7. In an extensible antenna adapted to be mounted on a vehicle and including a plurality of relatively movable telescopic sections electrically connected together, the inner of which is extensible from a retracted position within an outer section to an extended position, an actuating mechanism comprising a flexible cable secured to said inner section and having a helically threaded peripheral surface, a power-driven rotatable nut assembly continuously engaging the periphery of said cable to advance said inner section from its retracted position to its extended position and back to a retracted position, an abutment on said cable, and a stop spaced from said nut and engageable by said abutment to limit extension movement of said inner section.

8. In combination, an antenna having a plurality of electrically connected, relatively telescopically movable mast sections including an inner section axially movable from a lower retracted nonreceiving position to an upwardly extended signal-receiving position and an outer section telescopically axially receiving said inner section therein when said inner section is in its retracted position with the inner section projecting axially below said outer section, energizable power means for moving said inner section from either of said positions to the other of said positions and including an actuating member operatively connected to an electrically grounded power component and insulately connected to said inner section, said actuating member being axially extensible into said outer section upon energization of said power means to advance said inner section to its extended position and being retractible beyond the connes of said outer section upon retraction of said inner section, and an insulating sleeve interposed between said inner and outer mast sections, said sleeve electrically isolating the outer section from the actuating member upon extension of said inner section, said inner section portion projecting below the outer mast section being in electrically grounded relation to said power component when the inner mast is retracted to thereby ground out the antenna.

9. `In an extensible antenna adapted to be mounted on a vehicle and including a plurality of relatively movable electrically connected telescopic sections, the inner of which is extensible from a retracted position within an outer section to an extended position, an actuating mechanism comprising a exible driven cable secured to said inner section and having a helically threaded peripheral surface, a power-driven rotatable nut assembly continuously engaging the periphery of said cable for axially advancing the cable to extend said inner section from its retracted position to its extended position, a radially enlarged abutment on said cable, and a stop spaced from said nut and engageable by said abutment to limit extension movement of said inner section, said stop including an elastomeric grommet operatively engageable by said abutment and having an aperture accommodating passage of said cable therethrough.

l0. In combination, an antenna having a plurality of relatively telescopically movable mast sections including an inner section axially movable from a nonreceiving position to a signal-receiving position and an outer section receiving said inner section therein when said inner section is in its retracted position with a portion of the inner section depending beyond said outer section, energizable power means for moving said inner section from either of its said positions to the other of said positions and including an electrically grounded actuating member insulatedly connected to said inner section, said actuating member being extensible into said outer section upon energization of said power means to advance said inner section to its extended position and being retractible from said outer section upon retraction of said inner section, insulating means electrically isolating the outer section from the actuating member upon extension of said inner section, and means electrically grounding that portion of said inner section which projects below the outer mast section when the inner mast is retracted to thereby ground out the antenna.

11. A power-actuated antenna comprising an antenna section extensible beyond a surrounding case to enhance signal reception therethrough, an actuating cable having a threaded periphery of appreciable axial lead, insulated connecting means securing said cable to said antenna section against relative axial and rotational movement, rotary power means, and a driving assembly including a carrier driven by said rotary power means and encompassing a portion of the threaded periphery of said cable, and a plurality of lthread-engaging elements carried by said carrier and having toroidal peripheral portions en-' gageable with thecable to move the cable and the antenna section in a predetermined direction.

l2. In an extensible antenna having inner and outer relatively movable electrically connected telescopic sections, the inner of which is extensible from a retracted position within the outer section to an extended position at which most of the inner section projects beyond the outer section, a reversible motor having a shaft provided with an axial bore, an insulating sleeve interposed between said inner and outer sections and terminating short of said motor shaft, an actuating cable insulatedly secured to said inner section and projecting therefrom through the shaft bore of said motor, and a cable-engaging assembly drivingly secured to said motor shaft and engaging said cable to advance and retract said inner section thereby, said cable entering said outer section during extension of the inner section and being insuiated from said outer section by said sleeve, said inner section entering the bore of said shaft upon retraction o1` said inner section to .ground out the antenna through said motor.V

13. A vehicular antenna comprising an inner antenna section axially movable from a lower retracted nonreceiving position to an upwardly extended signal-receiving position and an outer antenna section telescopically axially receiving said inner section therein when said inner section is in its retracted position, means for electrically connecting said inner and outer sections,

energizable power means for moving said inner section and including a flexible push-pull cable insulatedly connected to said inner section, said cable being movable into said outer section upon energization of said power means to advance said inner section to its extended position, and electrical insulating means interposed between said inner and outer mast sections, said means electrically isolating the outer section from the actuating member upon extension .of said inner section, so that distortion of said cable within said outer section will not ground out the antenna through the cable.

14. In an extensible antenna adapted to be mounted on a vehicle and including'a plurality of relatively movable telescopic sections, the inner of which is extensible from a retracted positionwithin an outer section to an extended position, an actuating mechanism comprising a flexible driven cable secured to said inner section and having a helically threaded peripheral surface; and a power-driven rotatable nut assembly continuously engaging the periphery of said cable to advance Said inner section from its retracted position to its extended position and back to its retracted position.

References Cited in the tile of this patent UNITED STATES PATENTS 2,346,728 Carlson Apr. 18, 1944 2,368,298 Harris Jan. 30, 1945 2,439,411 Micheli Apr. 13, 1948 2,634,370 Carlson Apr. 7, 1953 

